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The mkiv Supra Owners Club

Crank balancing


hodge

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Hi guys

I've a few questions about this.

Over the coming months I'll be building myself a new engine, with some tasty pistons and rods this time. I'm just wanting to get my head around everything before I start bolting stuff together.

Firstly, Will a stock crank require balancing before I fit it or is it safe to say a stock Toyota crank will be balanced perfectly?

 

Secondly, This time I will be using a stock flywheel in apose to the lightened ORC clutch and flywheel I currently have fitted and also a Titan crank pulley which the instructions say MUST NOT be balanced as its already perfectly done, so if a stock crank does need doing, will I need to fit the flywheel, clutch, spigot bearing and crank dampner when I have it balanced?

 

Thirdly, how much does it cost to have a crank balanced, incase it needs doing so I can budget for it?

 

 

 

Thanks

John

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For optimum performance aren't you supposed to have the crank, rods, pistons and crank dampner all balanced together?

 

With lighter parts you could in theory run 10,000rpm with the same loadings as stock at 7,800rpm ;)

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For optimum performance aren't you supposed to have the crank, rods, pistons and crank dampner all balanced together?

 

With lighter parts you could in theory run 10,000rpm with the same loadings as stock at 7,800rpm ;)

 

I'm no expert on balancing engines but I know about static and dynamic balancing, not sure how you could balance a crank with its rods and pistons together, unless you didn't mean as an assembly.

Hodge mate, certainly get it balanced.

 

If it all needs balancing then that's what I'll do. I want a bulletproof engine, more for piece of mind really than anything else.

Let's hope Mr. wilson see's this thread and baffles us with loads of technical info.

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I would get the rods balanced along with the pistons and get the complete crank/clutch assembly

done as well.

 

Pistons will be a case of making them weigh exactly the same, this also goes for the rods but along with

making them weigh the same overall you balance them to weigh the same from the little end to the big end

and visa versa.

 

If you fitted a new crank you'd still get it balanced to a finer tolerance

Edited by Dnk (see edit history)
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I would get the rods balanced along with the pistons and get the complete crank/clutch assembly

done as well.

 

Pistons will be a case of making them weigh exactly the same, this also goes for the rods but along with

making them weigh the same overall you balance them to weigh the same from the little end to the big end

and visa versa.

 

If you fitted a new crank you'd still get it balanced to a finer tolerance

 

I'm going to have Chris balance my rods and pistons. I may as well speak to him about the crank too then.

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The proper way is to start with the crank on its own, new ones should have decent balance, but don't always, a proper balance will get it cock on. Then add ancillaries like flywheel, then damper, then clutch, blah blah. That way each item has perfect individual balance, so if the damper gets old or fails you just need to get a new damper checked for balance, rather than stripping the engine down completely. If balanced as an assembly one or more individual items can be well out of balance whilst the whole assembly is in perfect balance IYSWIM? It is definitely worth doing, and makes a noticeable differeence to how smooth and engine feels, and saves wear and tear. There are two people I trust for balancing, and both are quite dear, but a poor balance is no better than not bothering. VERY few people can ,ake a comptent job of V8's and V10's in the UK, I have seen some right disasters.

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Sounds fair enough to me Chris. Once I get all my parts together I'll take a drive down with the crank, flywheel, pistons and rods and I'll just get the lot done in 1 go. At least I know if I leave them with you they'll be spot on when there done.

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